An optical sensor based on covalent immobilization of 1-aminopyrene using Au nanoparticles as bridges and carriers

A novel technique of covalent immobilization of indicator dyes for the preparation of optical sensors is investigated. Au nanoparticles are used as bridges and carriers for anchoring indicator dyes on the surfaces of quartz glass slides (the substrates). 1-Aminopyrene was covalently attached to the outmost surface of the substrates via silanization, attachment of Au particles, self-assembly of HS-(CH2)11-OH, and coupling of 1-aminopyrene using cyanuric chloride. Thus, an aminopyrene-immobilized optical sensor was prepared and employed for determining picric acid. This sensor shows practically no dye-leaching, rapid response, high selectivity, good reproducibility and reversibility. The linear response to picric acid covers the range of 9.55 × 10−7 to 1.91 × 10−4 mol l−1 with a detection limit of 7.8 × 10−7 mol l−1. The covalent immobilization of 1-aminopyrene is an example of the proposed methodology which could be readily adaptable to other indicator dyes with primary amino groups.